Azamerocarbocyanine dyes



it Patented July'21, l953 T srAr-es PATENT ferries: 7

I Az MEiioc RBoo AN INE miss] Leslie G lsi -Br'ooker and FrankL White,- Rochester, N. Y.,,assign0rs to Eastman Kodak Com- I pany, Rochester, N.,Y., acorporation of New No Drawing. Application July 22,-1949; Serial No. 106,314 1 This invention relates to azamerocarbocyanine "dyes and to a process for preparing the-same;

a==rew azamerocarbocyanine dyes have ,been

prepared by condensing 4 (a-ethoxyethylidene) '3-methyl-l -phenyl :5-pyrazolone with 2-aminob enzothia'zole alkyl quaternary salts.

See British Patent 544,647, accepted'April. 22, 1942, for ,example. -Such azamerocarbocyanine dyes, have thefollowing-formula: V

in these known dyes the'nitrogen atom of v; f

group is not contiguous to the pyrazolone nucleus. We have now found azamerocarbocyanine dyes in which the nitrogen atom of the :HN= group is adjacent to the pyrazolone nucleus i While the az,amerocarbocyanine dyes-heretofore obtained are useful' in altering the sensitivity of I photographic-silver halide emulsions, many of the dyes of our invention have littleor no efiect when used as sensitizers for such emulsions. Quite unexpectedly, we have found, however, that many of,-;the dyes: of our"invention are excellent super-. 7

sensitizers-Ior certain :cyanine dyes, many of Whi0h" 'h'a VyIlQ sensitizing effect in their own accordingly an object of our invention to provide inew azamerocarbocyanine dyes; A'Yfurther-cbjectjisto provide a process for preparing suchdyes; Z Other, objects will become apparent rom a consideration of the following descripti on and examples. '-'The azamero'carbocyanine dyes 0f'our invenwherein R1 and R2 each represents 'an aryl group,

e; g. phen'yl; p-'tolyl,'m-tolyl, 'o-tolyl', pecarboxyphenyl, pesulfophenyl, m-carbomethoxyphenyl, m-ca'rb'ethoxyphenyl, 4- bromophenyl, 3 naph thyl, a n'aphthyl, *l-sulfo-a-naphthyl, etc. groups,

oran izalkyllg'roup,. e; g. methyl, ethyl, n-propyl,

12 'Claims. (c1. zed-e401) isopropyl, n-butyl, isobutyl, etc. -groups (e. g: an

alkyl group of the formula -CmH2m+1 wherein m is a positive integer from 1 to 4), R1 in addition represents a benzothiazolyl group, n represents a. positive integer from 1 to 2,-R3 represents an alkyl group (i. e. an alcohol radical), e. ,g. methyl, ethyl, n-propyl, isobutyl, n-butyl, n-amyl, isoamyl, B-hydroxyethyl', y hydroxypropyl, fl-methmethoxy-p-naphthothiazole, 5-ethoxy-fi -nap h-v oxyethyl, fi-ethoxyethyl, allyl (vinylmethyl); 18- methallyl (isopropenylmethyl) benzyl. (phenyl methyl), fi-phenylethyl, fl-carboxyethyl, carboxymethyl, a-carboxyethyl, v-carboxypropyl,:c-acetoxyethyl, -acetoxypropyl, carbomethoxymethyl, fi-carbomethoxyethyl, carbethoxymethyl'; fi-carbethoxyethyl, p-sulfoethyl, phenylmercaptomethyl, phenoxymethyl, p-phenylmercaptoethyl,

fi-phenox'yethyl, etc.,'and Z, represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series (e. g. thiazole, 4- methylthiazole, l-phenylthiazole, 5-methylthi a zole, 5-phenylthiazole, 4,5-dimethylthiazole, 1,5- diphenylthiazole, 4 '(2 e thienybthiazole, etc.), those of the benzothiaz-ole series (e. g.,benzothiazole, 4r-chlorobenzothiazole, 5 chlorobenzothiazole, 6, p-chlorobenzothia'zole, 7-chlorobenzothia- 'zole, 4-methylbenzothiazole, 5-methylbenzothiazole, G-methylbenzothi'azole,' 5-bromobenzothia zole, 6-bromobenzothiazo1e, 4-pheny1benzothiazole, 5-phenylbenzothiazole, i-methoxybenzothiazole, 5-methoxybenzothia'zole, 6-methoxybenzothiazole, 5-iodobenzo-thiazo1e, 6-iodoberizothiazole, lethoxybenzothiazole, 5-ethoxybenzothiazole,tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole,

5 hydroxybenzothiazole, 6' hydroxybenzothi azole, etc.), those of the naphthothiazole series (e. g. a-naphthothiazole, B-naphthothiazole, 5-

I those of the naphthoxazole series (e. g. ci-naphthoxazole, ,enaphthoxazole, etc.), those of the droxybenzoselenazole, tetrahydrobenzoselenazole,.

etc.), those of the naphthoselenazole series (e. g. a-naphthoselenazole, p-naphthoselenazole, etc.), those of the thiazoline series (e. g. thiazoline, 4

methylthiazoline, etc.), those of the 2-quinoline series (e. g. quinoline, 3-methylquinoline, 5-methylquinoline, 7-methylquinoline, 8 methylquinoline, 6 chloroquinoline, 8 chloroquinoline, 6

methoxyquinoline, 6-ethoxyquinoline,6-hydroxyquinoline, 8-hydroxyquinoline, etc.) those of the 4-quinoline series (e. g. quinoline, G-methoxyquinoline, 'Y-methylquinoline, 8-methylquinoline,

etc.) those of the l-isoquinoline series (e. g. iso- I quinoline, 3,4-dihydroisoquinoline, etc.) those of the 3-isoquinoline series (e. g. isoquinoline, etc), those of the 3,3-dialkylindolenine series (e. g. 3,3 dimethylindolenine, 3,3,5 trimethylindolenine, 3,3,7-trimethylindolenine, etc.), the pyridine series (e. g. pyridine, 5-methylpyridine, etc.), etc.

In addition, R; can represent an aryl group, e. g. phenyl, e-chlorophenyl, etc. when Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the thiazole, thiazoline, benzothiazole or 3,3-dialkylindolenine series.

According to the process of our invention, we prepare the compounds represented by Formula I above by condensing a cyclammonium quaternary salt with an isonitrosopyrazolone. As cyclammonium quaternary salts, those represented by the following general formula can be used:

wherein Z, R3 and n have the values set forth above, and X represents an anion, e. g. chloride,

bromide, iodide, thiocyanate, sulfamate, methylsulfate, ethylsulfate, perchlorate, benzenesulfonate, p-toluenesulfonate, xylenesulfonate, etc.

As isonitros-opyrazolones those represented by the followinggeneral formula can be used:

wherein R1 and R2 have the values set forth above. The compounds represented by Formula III can be prepared by reacting a pyrazolone selected from, those presented by the following eneral formula:

wherein R1 and R2 have the values set forth above, with sodium nitrite in the presence of acetic acid. 7

The condensations of our invention can advantageously be carried out in the presence of an alkali metal carboxylate, such as sodium acetate, potassium acetate, sodium butyrate, etc. (e. g. an alkali metal salt of a carboxylic acid containing from 2 to l carbon atoms) in a carboxylic anhydride, such as acetic, propionic, n-butyric,

v invention.

Example 1.--3 methyl 1-phenyl-4-[(1,3,3-trimethyl 2(1) indolylidene) -methyliminol 5- A mixture of 2.03 g. (1 mol.) of 4-isonitroso-3- methyl-l-phenyl-5-pyrazolone, 3.01 g. (1 mol.)-

of 2,3,3-trimethylindolenine methicdide, and 1.23 g. (1 mol+50% excess) of'fused sodium acetate in 15 cc. of acetic anhydridewas heated at the refluxing temperature for 5 minutes, and the reaction mixture-was chilled overnightat 0 C. It was stirred with several successive portionsof cold water. The crude residue was stirred with hot methyl alcohol, and the suspension was chilled at 0 C. The dye was washedonto the filter with methyl alcohol.* The yield of dye was 26% crude and 11% after two recrystallizations from methyl alcohol (220 cc. per gram of dye). The red crystals with green reflex had a melting p i t of ,205206? C. with decomposition, and softened at C.

Example 2.-4- (3-ethyl-2 (3) -a-naphthoxazolyltclene) methylimino] -3-methyl-1 phenyl 5- pyrazolcne I CH:

This dye was prepared exactly as the dye of Example 1,except that 3.39 g. (1 mol.) of Z-methyle-naphthoxazole ethiodide were used in place of the 2,3,3-trimethylindolenine methicdide. The dye was purified by dissolving it in 10.00. of pyridine and precipitating the dye by adding methyl alcohol. It was obtained as minute reddishorange crystals having a melting point of 214- 216 C. with decomposition.

Example -3.3 methyl 4-'[ (3-methyl-2(3) -thiazolinylidene)methylimino]-1 -phenyl 5 pyrazolone This dye was prepared exactly as the dye of Example 1, except that 3.43 g. (1 mol.) of 2- methylthiazoline methicdide were used in place of the 2,3,3 -trimethylindolenine methiodide. The yield; of dye after recrystallization from methyl alcohol (215 cc. per gram of dye) was and y it was obtained as red crystals with a green reflex. It had a melting point of 237-238 C. with decomposition.

Example 4.-4 [(3-ethyl-2(3)benzothiazolylidene)methyliminol-3-methyl I phenyl 5- pyrazolone CH: 02m

A mixture of 2103 g. (1 mol.) of 4-isofnitroso-3- methyl- 1-phenyl-5-pyrazolone, 3.49'g. v(1 mol.) of 2-methylbenzothiazole I Y etho-p-toluenesulfonate and 1.23 g. (1 mol.+50% excess) of fused sodium acetate in40 cc. of acetic anhydride was heated at the refluxing temperature for 3 minutes. The

cold reaction mixture was stirred with several Example 5-4-[(1-ethyZ-2(1)'ee-naphthothiazolylidene) methyliminol 3 -.methyZ-1-phenyl-5- A mixture of 2.03 g. .(1 mol.) of 4-isonitroso-3- I methyl-1-phenyl-5-pyrazolone, 2.89 g. (1 mol.) of

Z-methylbenzoxazole ethiodide and 1.23 g. (1 mol.+50% excess) of fused sodium acetate in 25 cc.of acetic anhydride was heated at the refluxing temperature for 10 minutes. The cold reaction mixture was stirred with severalsuccessive portions of cold water. The residue then was stirred with hot methyl alcohol. After chilling at 0 C., the solid was washed onto the filter with methyl alcohol. The yield of dye was 11% crude and 3% after two recrystallizations from methyl alcohol. The very dark crystals had a melting point of 220-222 C. with decomposition;

Example 7 .-4-.-[ (3 -ethz/Z-4-methyl-2(3) thiazoZ- ylidene) methyliminol 3 -methyZ-1-phenuZ-5 pyrazolone e r This dye was prepared in the same manner as the dye of Example 6, except that 2.6 g. (1 mol.) of 2,4-dimethylthiazole ethiodide were used in place of the 2-methylbenzoxazole ethiodide. The yield of dye was 34% crude and 14 after two recrystallizations from methyl'alcohol (215 cc. per gram of dye). The pure dye was obtained as dark red crystals with a green reflex and had a melting point of l86-187 C. with'decomposition.

Example 8.--1-(2-benzothiazoli1l) -4-[ (3- emyz- 2 (3) -.benzothiazolylidene) methylimino] 3 methyl-S-pyraeolone A mixture of 1.30 g. (1 mol.) of l-(2-benz0thiazolyl) -4-iso-nitroso-3-methyl-5-pyrazolone, 1.75 g. (1 mol.) of Z-methyI-benzothiazoleetho-p-toluenesulfonate and 0.62 g. (1 mol.+50% excess) of fused sodium acetate in 20 cc. of'acetic anhydride was heated at the refluxing temperature for about 2 minutes. stirred with several successive portions of cold water. The solid was collected on a-filter and washed With cold water. -The residue was stirred, in a. beaker, with methyl alcohol, and then washed onto a filter with methyl alcohol. This solid was dissolved in 30 cc. of pyridine and on cooling there separated 0.35 g. of 'dye. This portion was recrystallized from pyridine. The crystalline powder with green reflex was obtained in 14% yield, and it had a melting point above 300" C.

A mixture of 2.17 (1 mol.)'of 4-isonitroso-3- methyl-1-m tolyl-5-pyrazolone, 3.01 g. (1 mol.-).

of 2,3,3-trimethy1indolenine methiodide and 1.23 g.. (1 mol.+50% excess) of fused sodium acetate in 15 cc. of acetic anhydride was'heated at the refluxing temperature for about one minute. The cold reaction mixture was stirred with about 300 cc. of cold Water and the solid was collected per gram of dye).

on a filter and washed with cold water. The residue was stirred, in a beaker, with methyl alcohol. After chilling at 0 C'., the dye was washed onto the fllter with methyl alcohol. The yield of dye was 19% crude and 15% after two recrystallizations from methyl alcohol cc. The dark crystals with a The cold reaction mixture was 7 Z metallic reflex had a melting point of 203-204 C. with decomposition.

Example 1 0. 3-methyl-1 -p-tolyl-4 (1 ,3,3trimethyl 2(1) indolylidene) methylimino] -5- pyrazolone I Example 11.-4- (3-ethyZ-2 (3) -benzoselenaz lyZ- idene)methyliminol-3-methyl 1 phenyZ-- pyrazolone 7 o c v N o H 0 6 o=oHN=c N i I CH: 0211s A A reaction mixture consisting of 2.03 g. (1 mol.)v of 4-isonitroso-3-methyl-l-phenyl-5-pyrazolone, 3.52 g. (1 mol.) of Z-methylbenzoselenazole ethiodide, 1.23 g. (1 mol. plus 50% excess) of fused sodium acetate and cc. of acetic anhydride was heated at the refluxing temperature for-3 minutes. After chilling overnightat 0 C., the reaction mixture was stirred with several successive portions of cold water. The remaining residue was stirred with hot methyl alcohol and the resulting suspension was chilled at'0 C. The dye was collected on a filter and washed with methyl alcohol. The crude dye was extracted with 190 cc. of hot acetic acid and the remaining residue was dissolved in '70 cc. of pyridine. By chilling the pyridine extract 0.85 g. of. dy was obtained, and a further portion (0.45g.) was isolated by adding water to the pyridine filtrate. By chilling the acetic acid extract 0.30 g. of dye was obtained. The 0.85 g. portion wasrecrystallized from cc. of pyridine. By chilling the pyridine solution 0.37 g. of dye was obtained; The 0.45 g. and 0.30 g. portions were combined, dissolved in a small volume of pyridine and methyl alcohol was added to the pyridine filtrate. After chilling, the dye'was collected on a filter and washed with methyl alcohol. The dye weighed 0.60 g. and had a melting point of 225 227 C. with'decomposition. The dark green crystals gave a bluish-red solution in methyl alcohol.

Example 12.-1-(2-benzothz'azdlyl) 4 [(1,3-di-,

methyl 2(1) quinolylidene)methyliminol- 3-methyZ-5-pyrazolone OH: I

= 1.57- g. (1' mol.) of 2,3-dimethylquinoline' and 1.86-g. (1 mol.) of methyl p-toluenesulfonate were heated together at the temperature ofthe steam-bath for two days. To this crude quaternary salt were added 2.60 g. (1 mol.) of 1-.(2-

'benzothiazolyl) 4 isonitroso-3-methyl-5pyraz olone, 1.23 g. (1 mol. plus excess) of fused sodium acetate and 15 cc. of acetic anhydride. The reaction mixture was heated at the refluxing temperature for five minutes, cooled and stirred with ether. After chilling, the solids were collected on a filter and washed with ether. The residue was transferred to a beaker, stirred with cold water, and then the dye was collected on a filter and washed with water. After a similar treatment with methyl alcohol, the yield of dye was 2'7 crude and 22% after two recrystallizations from pyridine (50 cc. per gram of dye). The very dark green crystals had a melting point of 278279'C. with decomposition. The bluish pyridine solutionof this dye became purplish to reddish purple as water was added. Reversal of Kundtls rule.)

Example 13.1-(2-benzothiazolyl) -4-[ (1 -ethyl- 3 methyl-2 (1 -quinolylz'dene) methyliminol 3-methyZ-5-pyrazolone CzHs I CHa Example 14.-1 (z-benzothiazolyl) -3-methyZ-4- [.(1 meth-JZ-2. (1) -quino lyliden e) methylzminol 5-pyrazolone- This dye was prepared in a manner similar to that of Example 12, except that a molecularly equivalent amount of quinaldine metho-p-toluenesulfonate was employed in place of the 2,3- dimethylquinoline metho-p-toluenesulfonate of Example 12. The yield of dye was crude and 25% after two recrystallizations from pyridine cc. per gram of dye). The green crystals had amelting point above 300 C. This dye gave a purple solution in pyridine and a bluishred solution in methyl alcohol.

This dye was prepared in a manner similar to that of Example 12,. except that a molecularly equivalent amount of quinaldine etho-p-toluenesulfonate was used in place of the 2,3-dimethylquinoline metho p-toluenesulfonate.

The yield of dye was 36% crude and 24% after two recrystallizations from pyridine (50 cc. per gram of dye). The very dark green crystals had a melting point above 300 C. This dye gavea purple solution in pyridine and a bluish-red solution in methyl alcohol.

Example 1 6. 1- (Z-benzothiazolyl) -3-methyl-4-. (1-methyl 4. (1 -quinolylidene) methylimino] 5-pyrazolone I A reaction mixture consisting of 2.6a g. 1 mo1.) of 1-(2-benzothiazolyl) -4-isonitroso-3-methyl-5- pyrazoline; 2.85 g. ,(1 mol.) of lepidine methiodide.

' 1.23 g. (.1 mol. plus';50% excess) of sodium acetate and cc. of acetic anhydride was heated at the refluxing'temperature for 5 minutes. The cool mixture was stirred with ether. .Afterfchilling, the solids were collected on a'filter and washed with ether. The residue was transferred to a beaker, stirred with cold water, and then the dye was collectedon a filter and washed with water, I I Aftera similar treatment with methyl alcoholthe yield of dye was 43 %-crudeand2O after two recrystallizationsfrom pyridine (420 cc.per gram of dye). The very darkgreen crystals had a melting point of 303 304?v C. with decomposition. This dye gave a deep blue solution in pyridine and a purplish solution in methyl alcohol.

[(I-methyl- 2(1) pyridylidene) methyliminol S-pyrazolone f ing point or 303-304 C. with decomposition. 'Ihis dye gave a crimson solution in pyridine and' .a deep yellow solution in methyl alcohol.

' Example 1 4 I 4 (z-benzothiazol y l) -3-methyl-4 yellow crystals from pyridine had a melting point ii p Example 18. 1-(2 -beneothia'zolyl) -3-methyl-4- (z-methyl- 1 (2) -z'soquz'nolylidene) methylimino] 5-pymzolone This dye was prepared in a manner similar to that used in Example 16, except that a molecularly. equivalent amount of l-methylisoquinoline methiodide was employed in place of the lepidine methiodide in Example 16. The yield of dye was 55% crude and 40% after two recrystallizations from pyridine (60 cc. per gram of dye). The dark green crystals had a melting point of 261- 262? C. with decomposition. This dye gave a purple solution in pyridineand a reddish solution in methyl alcohol. y I

The isonitrosopyrazolones used in the above examples were prepared as follows: Example 19.-4-isonitroso-3-meth1/Z 1Wham L5- A cold solution of 13.8g. (1 mol.) of sodium nitrite in 50 cc. of water was addedto a chilled solution of 34.8 g. (1 mol.) of 3-methyl-l-phenyl- 5-pyrazolone in'75 cc. of acetic acid with stirring. The whole soon set to a stiff mass and 100 -cc. of Water was added'with stirring. The

I The first crop of light orange crystals weighed 32.3.g. and they had a melting point of 158- 7 Example 20.--1- (Z-Denzothiazolyl) -4-isonitroso.-

3-methyZ-5-pyrazolone A cold solution of 3.45 g. (1 mol.) of sodium nitrite in 25 cc. of water was added to a chilled suspension of 11.55 g. (1 mol.) of l-(2-benzothiazolyD -3-methyl-5-pyrazolone in 100 cc. of acetic acid with stirring. After standing at room temperature for 30 minutes the reaction mixture was chilled at 0 C. The solid was collected on a filter and washed with cold water. The greenishof 274-2 C. with decomposition.

Example 21.-4-i.sonitroso-3 methg/Z-1-ptolyZ-S-pyraeolone A cold solution of 3.45. g. (1 mol.)' of sodium nitrite in 25 cc. of water was addedto a chilled solution of 9.4 g. (1 mol.) of 3-methyl-1-p4PO1Yl- 5-pyrazolone in 50 cc. of acetic acid with stirring. Solid separated and 50 cc. of water was added with some stirring. The reaction mixture was allowed to stand at room temperature for 30 minutes and then chilled at C. The solid was collected on a filter and washed with cold water. The yield of .productwas 100% crude and 71% after two recrystallizations from methyl alcohol (8 cc. per gram of product). The light orange needles had melting point 180-l81 C.

Example 22.4-isonitroso-3-methyZ-1-mtolyl--pyrazolone I OH; This compound was prepared in the same man ner as the product of Example 21," except that a molecularly equivalent amount of 3emethyl-1- m-t01y1-5-pyraz0lone was used in place of' the, corresponding p-tolyl compound. After'rec'rystallization from ethyl acetate-it was obtainedas effect on such emulsionsQfFofr' example, while both 3-methyl 1 phenyl-e-l(1,3,3-trirnethyl-2- (1) indolylidene)methylimino] J5 pyrazolone (Example 1) and 3methyl-.l(D-sulfophenyl)-' 4 [(3-ethyl-2(3) -benzothiazolylidene').isopropylidenel-5-pyrazolone (L. G. SL'Brookr and F. L.

White, U. S. application Serial No. 605,472, filed sensitize photographic silver July 16, 1945) halide emulsions very weakly, a, combination of these dyes in a slow silver chlorobr'omiodideemulsion causes a marked increase in the speed} Some of the azam'erocarbo cyanine dyes of our invention are also useful in the preparation of photographic filter 'l ay'ersletci of the emulsion.

What we claim asour invention and desire secured by Letters Patent of the United States is: 1. A dye selected from those represented by the following general formula: Z O=(IJR 'NR1 m-fi YoH =oH n T'-o=cHN=o N wherein R1 represents a member selectedfrom the group consisting of a primary alkyl group of the formula CmH2m+1 wherein m represents a positive integer from 1 to 4, an aryl group of the benzene series, an aryl group of the naphthalene series and a benzothia'zolyl group, R2 represents a member selected from the group consisting of a primary alkyl group of the formula CmHZm-H wherein m represents a positive integer from 1 to 4, an aryl group, of the benzene series and an aryl group of the naphthalene series, n represents a positive integer from 1 to 2, R3 represents a, primary alkyl group .of the formula CmH2m+1 wherein m representsa positive integer from 1 to 4, and Z represents th non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of thethiazole series, those of the benzothiazoleseries, those of the naphthothiazole series, those'of-; the thionaphtheno-7',6,4,5-thiazole series, those of the oxazole series, those of the benzoxazole series, those'of the naphthoxazole series, those of the selenazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the thiazoline series, those of the 2-quinoline series, those of the i-quinoline series, those of the l-isoquinoline series, those of the'3-isoquinoline series, those of the 3,3-dialkylindolenine series and those of the pyridine series. i Y

2. The compound represented by thefollowing formula:

"'3. The dye represented by the following formula:

4. A process for preparing a methine dye comprising condensing in the'presence of anallgali metal carboxylate in a carboxylic-anhydride awherein R3 represents a primary alkyl group of the formula CmH2m+1 wherein m represents a positive integer from 1 to 4,1; represents aposi-' series," those of the benzothiazole'series, those of the naphthothiazole seriesfthos'e of thethionaph theno- 7 ,6,4,5-thiazole series,,those of the oxazole series, those of theibelnzoxazole series, those" ofthe naphthoxazole series, "thos of the selenazole series, those of the benzoselena'zole series, those of the naphthoselenazole series, those of the thiazoline series, those of the zquinoline series, those of the -quinoline series, those of the l-isoquinoline series, those of the 3-isoquinoline series, those of the 3,3-dialkylindolenine series and those of the pyridine series, with a ll-isonitrosopyrazolone selected from those represented by the following general formula:

wherein, R1. represents a member' selected from the group consisting ,ofia'p'rimary alkyl group of the vformula ,CmH2 m+1 wherein represents '9; 1 positive integer from 1 t0 4,'an aryl group of: the.

following general etho-p-tcluenesulfonate methyl-l-phenyl-S-pyrazolone.

13 benzene series, an aryl group of the naphthalene series and a benzothiazolyl group, and. R2 represents a member selected from th group consisting of a primary alkyl group of the formula CmH2m+1 wherein m represents a positive integer from 1 to 4, an aryl group of the benzene series and an aryl group of the naphthalene series.

5. The dye represented by the following formula:

O=O' NO6H5 o=oH-N=o N I CH3 7. Thedye having the following formula:

Ha C 2115 8. A process for preparing 1-[(3-ethyl-2(3)- benzothiazolylidene)methylimino] -3- methy1-1-. phenyl-5-py1'azolone comprising" condensing in the presence of an alkali metal carboXylat-e in a carboxylic anhydride 2 -methylbenzothiazole with 9. A process for preparing 4-[(3-ethyl-2(3)- a-naphthoxazolylidene) methylimino] -3-methyl- 1-phenyl-5-pyrazolone comprising condensing in the presence of an alkali metal carboxylate in a carboxylic anhydride 2-methyl-a-naphthoxazole' ethioolide with 4-isonitroso-3-methyl-l-phenyl- 5- pyrazolone.

10. A process for preparing 1-(2-benzothiazo1y1)-4- [(3-ethyl 2(3) -benzothiazolylidene) methyliminol-S-methyl -5- pyrazolone comprising condensing in the presence of an alkali metal carboxylate in a carboxylic anhydride Z-methylbenzothiazole etho-p-toluenesulfonate with 1-(2- benzothiazolyl) -4- isonitroso-S-methy1-5-pyrazclone.

11. A process for preparing 4-[(1-ethyl-2(1)- fl-naphthothiazolylidene)methyliminol -3-methyl-1-phenyl-5-pyrazolone comprising condensing in the presence of an alkali metal carboxylate in a carboxylic anhydricle Z-methyLfl-naphthothia- 4 isenitroso-3, q

zole etho-p-toluenesulfonate with 4-isonitroso-3- methyl-bphenyl-S-pyrazolone.

12. A process for preparing 4-[(3-ethyl-2(3)- benzoxazolylidene)methylirnino] 3 methyl-1- phenyl-5-pyrazolone comprising condensing in the presence of an alkali metal carboxylate' in a carboxylic anhydricle 2-methylbenzoxazole ethiodide. with 4-isonitr0so-3-rnethyl-1-phenyl-5- pyrazolone.

LESLIE G. S. BROOKER.

FRANK L. WHITEL References Cited in the'file of this patent UNITED STATES PATENTS 

1. A DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 